| 摘要 |
PROBLEM TO BE SOLVED: To obtain an yield and water-filtering property-improving agent composition for a paper-making not becoming a gel state on mingling a small amount of water and excellent in mechanical stability by preparing a composition containing a specific alkali soluble copolymer. SOLUTION: This yield and water-filtering property-improving agent composition for a paper making is prepared by including a dispersion of an alkali soluble copolymer obtained by copolymerizing 10-60 wt.%α,β-unsaturated ethylenic monomer having 0.2-30 wt.% solubility in water at 25 deg.C, e.g. methyl acrylate, 40-90 wt.%α,β-unsaturated carboxylic acid, e.g. (meth)acrylic acid and <30 wt.% another monomer copolymerizable with the above both monomers, e.g. (meth)acrylamide, and has 5 wt.% solid portion concentration and at least 400 mPa.s viscosity (BM type viscometer) at 25 deg.C. After adding the above composition and further a multi-valent metal salt such as aluminum sulfate, and a cationic substance such as a cationic polymer into a pulp slurry in a paper-making system at pH 6-9, the paper is made.
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